1. Field of the Invention
The present invention relates to a head suspension having a base plate, a load beam, and an actuator element to move the load beam relative to the base plate.
2. Description of Related Art
Small-sized, precision information devices are rapidly advancing, and for use with such devices, needs for micro-actuators capable of conducting positioning control for very small distances are increasing. Such micro-actuators are highly needed by, for example, optical systems for correcting focuses and inclination angles, ink jet printers for controlling ink heads, and magnetic disk drives for controlling magnetic heads.
In particular, the magnetic disk drives are rapidly expanding market and improving performance, and accordingly, are strongly needed to increase their storage capacities. Increasing the storage capacity of a magnetic disk drive is achievable by increasing the storage capacity of each magnetic disk contained in the magnetic disk drive.
The storage capacity or recording density of a magnetic disk will increase, without changing the diameter thereof, if the number of tracks per inch (TPI) on the magnetic disk is increased.
For this, a magnetic head of a head suspension installed in the magnetic disk drive must conduct a precise positioning operation in a direction across the tracks, i.e., a sway direction. For realizing the precise positioning operation, an actuator capable of accurately moving and positioning the magnetic head in a very small area is needed.
Head suspensions adopting precise positioning actuators are disclosed in Japanese Unexamined Patent Application Publications No. 2002-50140 and No. 2002-197819.
According to these related arts, the head suspension has a base plate, a load beam, and an actuator element that is energized to move the load beam in a sway direction relative to the base plate. The load beam is provided with a flexure having wiring. The wiring of the flexure is electrically connected through, for example, wire bonding to the actuator element.
The wire bonding, however, restricts the degree of freedom in choosing a connecting direction between the actuator element and the flexure.
To widen the degree of freedom in choosing a connecting direction, the applicant of the present invention has proposed a head suspension illustrated in FIG. 10.
The head suspension has actuator elements 101a and 101b that deform in response to applied electric power, to move a load beam 105 relative to a base plate 103. Along a side of the base plate 103, a flexure (wiring member) 107 is arranged toward the load beam 105. The flexure 107 is electrically connected through a jumper 109 to the actuator elements 101a and 101b. 
The jumper 109 has connectors 111a and 111b connected to the actuator elements 101a and 101b, respectively, an intermediate part 113 extending over a base plate edge 103a of the base plate 103, and a connector 111c connected to the wiring of the flexure 107.
The jumper 109 widens the degree of freedom in choosing a connecting direction between the actuator elements 101a and 101b and the flexure 107. The jumper 109 functions to supply power from the flexure 107 to the actuator elements 101a and 101b. 
The jumper 109, however, has a risk of causing a short circuit at the base plate edge 103a. 
FIG. 11 is an enlarged sectional view illustrating a part XI of FIG. 10. The jumper 109 is composed of an insulating cover layer 113, a conductor layer 115, an insulating layer 117, and a metal layer 119 laid one on another from a base plate surface 103b side of the base plate 103.
Due to vibration and displacement of the actuator elements 101a and 101b, the insulating cover layer 113 of the jumper 109 wears on the base plate edge 103a, to cause a short circuit.
To reduce the abrasion of the insulating cover layer 113, the metal layer 119 serving as a rigidity backup may be removed to decrease the pressing force of the jumper 109 applied to the base plate edge 103a. 
This technique may slow the wearing of the insulating cover layer 113. However, it is impossible to eliminate the risk of causing a short circuit.
If the base plate edge 103a is close to any of the connectors 111a, 111b, and 111c of the jumper 109, the pressing force of the jumper 109 on the base plate edge 103a will not decrease and the insulating cover layer 113 of the jumper 109 will wear to cause a short circuit.